Biostatus and Distribution

This distinctive adventive ladybird from Australia, Pacific Islands and South East Asia was first found in Auckland in 1966. It has been found on Little Barrier Island and is common in the Auckland Region where it can be seen in parks and gardens on trees, shrubs and other plants infested with aphids.

Conservation status: This adventive ladybird is present in the Auckland Region and feeds on adventive aphids and it may assist with control of aphids on economic and ornamental plants.

Life Stages and Annual Cycle

The distinctly coloured adults are about five millimetres long. The head, prothorax (first part of the middle body) and elytra (wing covers) are orange and black with the black markings forming a cross on each elytron. Under the elytra is a pair of wings used for flying. The legs are black at their base and mid brown on the distal segments. The small head has a pair of compound eyes and two short antennae. The antennae and palps are also brown.

Female ladybirds lay yellow eggs near infestations of prey. A long larva hatches from each egg. The newly hatched larva is dark grey and has short dark tubercles. Older larvae have areas of white and pale yellow. The first abdominal segment is white laterally, while the fourth abdominal segment is white on top and on the sides. There are three pairs of legs. Larvae also use the tip of the abdomen for holding onto the substrate on which they are walking. As the larva grows, it moults (changes skin). There are four larval instars (stages). When the fourth larval instar is fully grown, it attaches itself to a sheltered place on a plant and moults into a pupa. The pupa background colour varies from pale to mid brown. The black spots and patches are more sharply defined on the pale pupae. The moulted larval skin remains at the base of the pupa. Adults hatch from pupae and mate. The length of time of each life stage depends on temperature, being shorter at higher temperatures.

Annual cycleThe ladybird probably overwinters (May-September) as adults. New season eggs are laid in spring. There are at least three generations per year in Auckland.

Walking and flyingBoth adult and larval stages of this ladybird have three pairs of legs that can be used for walking. Larvae also use the tip of the abdomen for holding onto the substrate. Adults have wings and can fly.

FeedingThe adult and larval ladybirds eat aphids and possibly other small insects. The jaws are the primarily structures used for holding and chewing the prey, and in this species of ladybird the front legs of larvae are also used for holding food.

Recognition

In New Zealand adult variable ladybirds are easily recognised by their circular shape and black cross like pattern on the orange-red elytra (wing covers). In Australia the pattern of black on the elytra is variable, hence the common name and many synonyms.

The larvae can also be recognised by the pale yellow and white pattern on the darker body. Two features of all larvae are lateral white spots on the first abdominal segment and white on the side and top of the fourth abdominal segment. The pupae are variable, but distinctive. They can be pale yellow brown with black spots or a more uniform darker brown.

Natural Enemies

No natural enemies of the variable ladybird are known in New Zealand. They are probably preyed upon by birds, spiders and predatory insects.

Honeydew Feeding

Adults have been found in late summer in association with Pittosporum psyllid, Trioza vitreoradiata (Maskell, 1879) (Hemiptera: Triozidae). They may have been feeding on the honeydew.

Prey/Host

Both adults and larvae feed on aphids. They are associated with aphids on trees and shrubs. The jaws are the primarily structures used for holding and chewing the prey, and in this species of ladybird the front legs of larvae are also used for holding food.

Additional Information

Biological control of pestsIn gardens and parks this ladybird contributes to the control of aphids on trees and shrubs. For example, it can be seen in colonies of the yellow aphid, Aphis nerii Boyer de Fonscolombe, 1841 (Hemiptera: Aphididae) on swan plants.

If pesticides are needed to control other pests, it is advisable to use chemicals that will have minimal harmful effects on the ladybirds or to use them at a time when the ladybirds are not present.

Diverse habits of 'ladybirds'Not all ladybirds eat insects; some feed on mites. Other species eat plant leaves and are pests especially in some tropical countries, whereas other ladybirds feed on fungi. One of these, Illeis galbula (Mulsant, 1850), from Australia, feeds on powdery mildew fungi. In New Zealand it is common on pumpkins and other cucurbits, plants that are commonly infected by powdery mildews. A plant feeding ladybird, hadda beetle (Epilachna vigintioctopunctata (Fabricius, 1775)) recently established in Auckland feeds on plants in the Solanaceae (potato family).

Information Sources

Nicholson AH 1971. A new coccinellid (Coleoptera) record for New Zealand. New Zealand Entomologist 5(1): 79-81.